Ecological perspective of the diversity of functional responses

Abstract

Prey-predator interactions have been modelled by numerous workers. Ecologists have continuously modified Lotka-Volterra equations in order to provide more realistic descriptions of the complexity of these interactions. The response of predator(s) to increasing prey density can be best described in terms of a functional response, which is an important criterion determining the success or failure of predator(s) to control fluctuating prey populations. The functional response of a predator is further differentiated into Holling's Type I, II, III, IV and V. We discuss one-prey and one-predator interactions, in which the models are modified by the inclusion of steady-state satiation and growth factors. We review situations where two prey and one predator interact, and vice versa. We also discuss Holling's Type IV model relevant to competition and food chains. There is a need to examine functional responses as these models were mostly developed by pure mathematicians and their relevance to field conditions remains largely untested. Prey-predator interactions can be affected even by small factors and ecologists should include these models in their experimental design when attempting to predict realistic interactions.

The primacy of temporal dynamics in driving spatial self-organization of soil iron redox patterns

“…However, when Fe(III) develops into plinthite-like aggregates, they do become a barrier for root growth. Such threshold-dependent responses are common in nature ( 59 – 61 ), suggesting that coupled SDFs shown in this study might be generalizable to many spatially self-organized systems.…”

The Primacy of Temporal Dynamics in Driving Spatial Self-organization of Soil Redox Patterns

“…This makes the inhibitory feedback thresholddependent. Threshold-dependent responses are common in nature (47)(48)(49); however, their effects on Turing morphogenesis have seldom been investigated. The most plausible mechanism of redox patterning in upland soils is the coupling of two sets of SDFs-clay-mediated SDF amplifies Fe(III) aggregation and crystallinity to the state that suppresses root growth.…”

“…At our study site, goethite in SOM-enriched gray layers has a much lower crystallinity than it does in the SOM-depleted orange layers (44). Coupled SDFs are likely generalizable to many self-organized systems where SDF are threshold dependent, a functional form common in nature (47–49).…”

Extinction and permanence of the predator-prey system with general functional response and impulsive control

“…The dynamic system is said to be hybrid when it exhibits continuous and discrete dynamics [3,4], and it is termed as a switched system when it consists of a family of subsystems in which the dynamics is switched among the subsystems according to a logical rule [2,[5][6][7][8][9][10]. The interactions of prey and predator, such as the study of the populations in the crops and pests system, is a simplified special case of the dynamic systems which has been investigated extensively in the ecological, agricultural and environmental research within the past few decades [11][12][13][14][15]. Particularly, the research on the pest control has been a popular topic as it imposes significant impacts on the social and economic stability of the region in question [16][17][18].…”